1. Field of the Invention
The subject invention relates to a unitized wheel hub and bearing assembly for the wheel end of a vehicle axle, and more particularly, to a lubricant condition monitoring system disposed within the wheel hub of a heavy-duty truck or trailer.
2. Background of the Related Art
The safe operation of heavy highway transport vehicles such as trailers and trucks has become a high priority to operators and regulatory authorities with an increase in the number of accidents and resulting fatalities to vehicle operators and motorists caused by the detachment of the wheel hub assemblies from vehicle axles. This catastrophic event most often results from the failure of a wheel bearing or associated component due to excessive wear or overheating caused by a loss in lubricant integrity.
The longevity and safe operation of a wheel hub assembly and associated bearings is highly dependent on the integrity of the lubricant contained within the wheel hub. As additives in the lubricant are depleted, or the base stock of lubricant degrades due to moisture or extreme heat, the lubricant is less effective in protecting the axle and wheel hub assembly components from damage caused by friction between moving parts. Lubricant degradation is especially problematic for heavy highway transport vehicles, which typically travel for long durations and great distances with heavy loads. These conditions are likely to accelerate the deterioration of the lubricant within the wheel hub assembly.
Most motorists routinely inspect and perform regular maintenance on their vehicles. Indeed, drivers of heavy highway transport vehicles must also submit to inspections by regulatory authorities in which the sole aim is to identify vehicles that are not being properly maintained. However, the construction of the wheel hub assembly of a truck or trailer does not permit easy access for interior inspection. This poses a significant safety problem because the lubricant within the wheel hub assembly may be insufficient or severely degraded to the point at which an equipment failure may soon occur, even though the vehicle appears properly maintained. Because the condition of the lubricant within the wheel hub is undetectable by an inspector or the vehicle operator, an accurate assessment of the health of the wheel hub assembly cannot be adequately obtained.
Therefore, there is a need for a system that is adapted and configured to monitor the condition of the lubricant within a wheel hub assembly of a vehicle so as to enable the detection of potential problems that may cause failure of or damage to the components of the wheel hub assembly.
The subject invention is directed to a new and useful apparatus for monitoring the condition of a fluid lubricant contained within the lubricant chamber of a wheel hub mounted for rotation about a stationary wheel axle of a vehicle, such as, for example, a heady duty truck or trailer. The apparatus includes an annular bearing spacer configured to be mounted on the wheel axle between the axially opposed inboard and outboard bearings which support the wheel hub for rotation about the wheel axle. The annular bearing spacer forms an interior lubricant reservoir between an inner surface thereof and the wheel axle.
A guide vane is provided for directing lubricant from the lubricant chamber to the interior lubricant reservoir during rotation of the wheel hub assembly about the wheel axle, and sensing means are operatively associated with the interior lubricant reservoir for determining the condition of the lubricant directed into the interior reservoir by the guide vane. In addition, means are operatively associated with sensor for communicating a signal corresponding to a determined condition of the lubricant to a remote location or data retrieval device.
The annular bearing spacer has at least one inlet port formed therein to facilitate the ingress of lubricant into the interior reservoir from the guide vane, and at least one outlet port is formed therein to facilitate the egress of lubricant from the interior reservoir. Preferably, filtering means are operatively associated with the at least one outlet port to filter the lubricant that egresses from the interior reservoir into to the lubricant chamber.
The guide vane extends radially outwardly from an outer surface of the annular bearing spacer and is configured to direct lubricant from the lubricant chamber to the interior lubricant reservoir upon rotation of the wheel hub about the wheel axle. The guide vane includes fluid passages for receiving lubricant from the lubricant chamber as the wheel hub rotates about the wheel axle and for directing the lubricant radially inwardly toward the interior lubricant chamber. In addition, the guide vane includes axial discharge ports in communication with the fluid passages for directing lubricant in an axial direction toward the inboard and outboard bearings as the wheel hub rotates about the wheel axle.
In accordance with one aspect of the subject invention, the sensing means is adapted and configured to sense the presence of metallic and non-metallic particles in the lubricant, providing an indication of the state of the wheel hub in general and the bearings in particular. In accordance with another aspect of the subject invention, the sensing means is adapted and configured to sense the conductivity of the lubricant, providing an indication of the integrity of the lubricant. It is envisioned and well within the scope of the subject disclosure that the sensing means may be adapted and configured to sense other lubricant conditions such as, for example, antioxidant depletion, temperature or lubricant viscosity. In accordance with the subject disclosure, the measured lubricant conditions may be used to determine the lubricant integrity by obtaining values such as the remaining useful life of the lubricant.
The subject invention is also directed to a method of monitoring the condition of a fluid lubricant contained within the lubricant chamber of a wheel hub of a vehicle. The method includes the steps positioning a lubricant condition sensor within the lubricant chamber of a wheel hub, determining a condition of the lubricant within the lubricant chamber of the wheel hub, and communicating a signal relating to the condition of the lubricant within the lubricant chamber of the wheel hub. The step of determining the condition of the lubricant includes, among other things, sensing the presence of metallic particles in the lubricant, or sensing the conductivity of the lubricant.
These and other unique features of the in-hub lubricant condition monitoring system of the subject invention will become more readily apparent from the following description of the drawings taken in conjunction with the detailed description of the preferred embodiments.